The present invention relates to a part sensor for a sagger loader and conveyor apparatus in general and more particularly to a part sensor for an apparatus for automatically conveying powder compacted articles or parts from a powder compacting press, or other apparatus, to saggers in which the parts are automatically loaded in a specific order, by rows for example, the saggers being supported by an indexing moving conveyor belt.
Most articles and parts compacted of powder material in a powder compacting press are ultimately loaded in ceramic boats or saggers which are used for conveying the parts through a "firing" or sintering furnace. The parts, prior to sintering, are in a so-called "green" state wherein the particles of powder material are held in adhesion by a binder, and they are therefore relatively fragile.
Safe mechanical handling of such fragile parts presents many problems when the parts are transferred to a loading station, for example, where they are loaded in even rows in saggers and subsequently transported in the saggers to a sintering furnace. In view of the difficulties encountered in handling such fragile parts, manual sorting of the parts and manual loading of the saggers are often the solutions dictated by the necessity of avoiding damaging the parts when in their green and fragile state. The problem of appropriately loading saggers with fragile parts is further complicated by the fact that the parts must be placed in a regular order in the saggers, rather than in bulk at random, sometimes spaced apart, such as to allow the sintering operation to be effected under good conditions, with adequate air or inert gas circulation around the parts, without fusing the parts in a mass, and with even heating and cooling of the parts during travel through the sintering furnace and during any subsequent heat treatment operation, such as quenching for example.
One problem associated with automatic loading of saggers with unsintered powder compacted parts is that it is desirable not to load the sagger with defective or broken parts and, when the parts are loaded in rows in a sagger provided with a bottom tray having cavities for holding the parts in a substantially vertical position, a part may fall over because of incorrect positioning of the part relative to a holding cavity, incorrect dimensioning of the holding cavity, or for any other reason. As the fallen-over part is disposed over empty holding cavities, it prevents further regular loading of the tray in the sagger and may cause further breakage of or damages to the parts.